Effect Of Endotoxin On The Permeability Of Blood-Labryinth Barrier And Protection With L-NAME Treatment In Guinea Pigs

Objectives: To evaluate the dynamic changes in the morphology and function of blood-labyrinth barrier (BLB) in endotoxin (ETX)-treated cochlea of guinea pigs, and to study the possible role of nitric oxide on the duration of the changes in permeability of BLB in ETX-treated cochlea. The investigation of ETX on BLB peameability may provide the theoretical basis for the mechanism of inner ear impairment resulting from suppurative otitis media-mastoedea.Methods:One hundred thirty-five healthy closed colony guinea pigs weighing between 150 and 200g were used in this study. All animals were confirmed to have a positive Preyer's reflex and no otitis media. The animals were randomly divided into three groups, normal saline, ETX and NG-nitro-L-arginine methyl ester (L-NAME)/ETX group. In the saline group (n=45,90 ears) 200ul saline was injected into each tympanic cavity via superior bulla. Inject each tympanic cavity 200ul saline containing 1mg ETX in the ETX group (n=45,90 ears). In the L-NAME/ETX group (n=45,90 ears) 200ul saline with1mg ETX and 1mg L-NAME was injected into each tympanic cavity. Every group was randomly divided into three subsection 12h,24h,72h group after the injection. Evans blue was injected via cervical vein to five guinea pigs in every subsection 2h before sacrificed. All animals were sacrificed 12h, 24h, 72h after administration. To detect the content of EB in BLB 24h after the cochleas were immersed in formamide. To observe morphological changes by light microscope and detect the changes of iNOS in cochlea by immunohistochemistry. Ultrastructure of stria vascularis and spiral ligament was observed by transmission electron microscope. The content of nitric oxide in cochlea was detected by nitrate reductase technique with ultraviolet spectrophotometer.